In the field of clinical laboratory tests, a system is used to perform pretreatments such as the pipetting of a primary sample to make aliquot samples prior to analytical processing including biochemical analyses and immunoassays of blood, urine and other samples. For such pretreatment systems, the volume of collected samples has increased in recent years along with an increasing number of items to be analyzed, and multiple primary samples have come to be collected. As a result, there has been a growing need for the capability to prepare aliquot samples from multiple primary samples. This need is met, for example, by an apparatus that transfers multiple primary samples on a sample transfer rack so as to pipette the multiple primary samples to make multiple aliquot samples (see Patent Literature 1).